Hole in #3 piston

[bwilly]

Less than 20 hrs on rebuilt engine. After pulling tube a couple of hours I discover hole burned in # 3 piston and scored cylinder.
How?
1 and 2 look good but noticed rubber shavings on all 3 around the o-rings in the head.
Why?
What can I do to prevent this from happening again?
Stock motor with R&D o-ring head.

[WATERCRAFTSERVICES]

Re: Hole in #3 piston

You Detonated The Piston. Did You Rebuild Carbs? You Are Getting A Lean Condition In That Cylinder. Possible Air Leak Or Carb Problem. Your O Rings Are Not Sealing. The Shavings Are A Result Of Escaping Gases Deterioating The O Rings. Have Seen This Problem Before On O Ring Heads. Be Sure The Head Is Not Warped And The Cylinder Decks Are Not Warped.